JPH1121223A - UV reflective powder and cosmetic containing it - Google Patents

Abstract

(57) Abstract: A monodisperse powder which forms a regular structure when applied and has UV-selective reflectivity, and a cosmetic containing the same. [Effect] High transparency and excellent UV protection effect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monodispersed powder having high transparency and excellent UV protection effect, and a cosmetic containing the same.

[0002]

2. Description of the Related Art Conventionally, in sunscreen cosmetics, inorganic powders or organic ultraviolet absorbers have been used as UV screening agents. Among these, as the inorganic powder, for example, zinc oxide, titanium oxide, cerium oxide and the like are used,
Ultraviolet rays are shielded by utilizing absorption or scattering of light peculiar to powder. Organic compounds having absorption characteristics in the UV wavelength range are used as organic ultraviolet absorbers.

[0003] In addition, the fine particle powder used as a UV cosmetic base material has a nonuniform particle size or is an aggregate of secondary particles, so that the concealing rate on the skin is low, and the The expected UV protection effect cannot be obtained. As a result, at the level of the powder necessary to obtain a high UV shielding effect (SPF level), there is a heavy and unpleasant feeling of use,
It also causes a white / blue residue on the skin. In particular, metal oxide powders, which are widely used as sunscreens for cosmetics, have a very large cohesive force and easily cause such a problem.

Further, in conventional sunscreen cosmetics, emphasis is placed on protection against UVB light (280 nm to 320 nm) which causes large damage to the skin (sunburn, skin cancer, photoaging), and a higher SPF value (Sun protect).
Products with a high ion factor have been developed. In recent years, photoaging of UVA light (320 nm to 400 nm),
The effect on skin cancer is also regarded as a problem, and the PFA value (pr
Development and commercialization of cosmetics with a high protection factor of UVA are also being carried out. However, since the wavelength of the reflected / absorbed light of the powder is unique, and few of them have the property of reflecting / absorbing UVA light, organic UV absorbers have been developed as UVA light absorbers. Due to problems such as stability, irritation to the skin, etc., it is impossible to formulate a high concentration.

[0005] On the other hand, it has long been known that light is diffracted when light is incident on the ordered structure layer formed by the monodisperse particle powder. For example, a diameter of 0.15 μm to 0.40 μm
When m monodisperse spherical particles form an ordered structure, the surface of the particle layer emits monochromatic light having a vivid metallic luster by diffraction of visible light. In this coloring phenomenon, it is important that the monodisperse particles are regularly arranged, and the material thereof is not particularly limited. Therefore, it is important to select monodisperse particles having excellent stability.

When a monodisperse particle powder forms a crystal lattice-like regular structure layer at a plane interval of d, and light is perpendicularly incident on this particle layer, the light diffraction is similar to the X-ray diffraction of a crystal. Happen

[0007]

Λ = 2n · d (1)

[0008] The light having the wavelength λ that satisfies the above condition is reflected most strongly. Here, n is the refractive index of the particles in the light particle layer. d varies depending on the arrangement of the monodisperse particles,
If the arrangement is the same, it is proportional to the particle size (particle size). For example, when spherical monodisperse particles having a diameter D are arranged in a face-centered cubic lattice and a (1,1,1) plane appears on the surface of the particle layer, d is

[0009]

(Equation 2)

[0010] Among powders used as cosmetic raw materials, there are few monodispersed powders having a uniform particle diameter, and there is no example of applying the above-described diffraction phenomenon to UV cosmetics.

[0011]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a monodisperse powder having high transparency and excellent UV protection effect.

[0012]

Under these circumstances, the present inventors have conducted intensive studies and as a result, have found that when coated, a monodisperse powder which forms a regular structure and has a UV selective reflection ability is obtained. By having high transparency and excellent UV protection effect, and by changing the particle size of the monodispersed powder,
The inventors have found that the wavelength of diffracted reflected light observed when a regular structure is formed can be changed, and that light from UVB to UVA can be selectively and strongly reflected, and the present invention has been completed.

[0013] That is, the present invention provides a monodispersed powder which forms a regular structure when applied and has UV-selective reflectivity, and a cosmetic containing the same.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The monodispersed powder of the present invention first forms a regular structure when applied. Here, coating refers to applying a dispersion of a monodispersed powder to a solid surface, particularly a skin surface, to evaporate a volatile dispersion medium. At this time, the regular structure formed by the powder refers to a crystal lattice-like structure formed when uniform powder is filled, and is preferably a regular structure layer that emits reflected diffraction light. . Such a regular structure can be confirmed, for example, by measuring a reflection spectrum.

In the monodispersed powder of the present invention, the regular structure formed upon application has UV selective reflection ability. Here, the UV selective reflectivity is 25 wavelengths.
Those capable of reflecting light in the UVB to UVA region from 0 to 400 nm are preferred. The light reflected by the regular structure of the monodisperse particle powder can be measured by applying the powder dispersion onto a glass plate and using the apparatus shown in FIG. Further, the wavelength of the reflected light can be changed by adjusting the particle size of the powder and controlling the surface spacing of the regular structure layer. That is, as the particle size is smaller, the intensity peak of the reflected light shifts to the shorter wavelength side.

The transmitted light of the monodispersed powder can be measured using a spectrophotometer by forming the powder dispersion into a film having a thickness of 0.1 mm on a quartz plate. The transmittance in the visible region reflects the transparency of the powder, and it is preferable that the transmittance be as high as possible. The transmittance at a wavelength of 500 nm is preferably 70% or more. On the other hand, the transmittance of UV light having a wavelength of 250 to 400 nm is preferably low, and is preferably 50% or less.

In the monodispersed powder of the present invention, the term "monodispersed" means that the shape and size of each particle are well-aligned. The powder preferably has an average particle size of 0.1 to 0.3 μm, particularly 0.15 to 0.25 μm, as measured by a dynamic light scattering method, and has a particle size distribution (weight average particle size / (Number average particle size) is preferably 1.50 or less, particularly preferably 1.10 or less. Within these ranges, a regular structure layer is easily formed, and the UV reflection effect due to the structure is large, which is preferable. Further, the particle shape is preferably spherical.

The material of the monodispersed powder of the present invention is not particularly limited, and may be any of inorganic powders, organic powders, and composite powders thereof, such as titanium oxide, zinc oxide, cerium oxide, silica, and sulfuric acid. Inorganic powders such as barium, alumina, aluminum hydroxide, calcium carbonate, and magnesium silicate; polymer particles that can be prepared by emulsion polymerization, soap-free emulsion polymerization, suspension polymerization, dispersion polymerization, and the like;
A composite particle powder in which a polymer (organic resin) is coated around an inorganic powder is exemplified. Among these, a composite particle powder obtained by coating an inorganic powder with a polymer is particularly preferable.

Preferred monomers for use in preparing the polymer particles include, for example, styrene, vinyltoluene, divinylbenzene, ethylene, propylene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile, (meth) acrylamide; (Meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, benzyl (meth) acrylate, lauryl (meth) acrylate, oleyl (meth) acrylate, palmityl (meth) acrylate, stearyl ( (C1 to C20) of (meth) acrylic acid such as (meth) acrylate
Examples thereof include alkyl or (C3-C20) alkenyl esters.

The monodispersed powder of the present invention has high transparency and excellent UV protection effect, and therefore can be suitably used as powder for various cosmetics. In this case, when the cosmetic is applied to the skin, the monodispersed powder forms a regular structure on the skin and can selectively reflect UV.

The cosmetic of the present invention preferably contains 0.1 to 50% by weight, more preferably 0.1 to 25% by weight, and more preferably 1 to 20% by weight of the monodispersed powder in the whole composition. Then, it is preferable because the transparency is high and the UV reflection efficiency is high.

The cosmetic of the present invention can be produced according to a usual method except that the above monodispersed powder is blended.
In order to further enhance the V-reflecting ability, other UV absorbers used in ordinary cosmetics can be appropriately blended within a range that does not impair the diffracted light by the ordered structure layer of the monodisperse particle powder.

The other UV absorber used herein is not particularly limited, and any of commonly used ultraviolet scattering agents, oil-soluble ultraviolet absorbers, and water-soluble ultraviolet absorbers can be suitably used. Among them, examples of the ultraviolet scattering agent include titanium oxide, fine particle titanium oxide (JP-A-57-67681), zinc oxide, fine zinc white (JP-A-62-228006), and flaky zinc oxide ( JP-A-1-175921), iron oxide, fine particle iron oxide, cerium oxide, zirconium oxide and the like.
These may be surface-treated with silicone, metal soap, N-acylglutamic acid, perfluoroalkyl phosphate, or the like. Their shape, size and form are not particularly limited, and they may be used in the form of a sol or the like.

As the oil-soluble ultraviolet absorber, benzoic acid-based para-aminobenzoic acid (hereinafter referred to as PA) can be used.
BA), glyceryl PABA, ethyl dihydroxypropyl PABA, N-ethoxylate PABA ethyl ester, N-dimethyl PABA ethyl ester, N
-Dimethyl PABA butyl ester, N-dimethyl PA
BA amyl ester, octyl dimethyl PABA and the like;
Anthranilic acid-based homomenthyl-N
-Acetylanthranilate and the like; salicylic acid-based ones, such as amyl salicylate, menthyl salicylate,
Homomenthyl salicylate, octyl salicylate, phenyl salicylate, benzyl salicylate, p-isopropanol phenyl salicylate, etc .; cinnamic acid-based octyl cinnamate, ethyl-4-isopropyl cinnamate, Ethyl-2,4-diisopropylcinnamate, methyl-2,4-diisopropylcinnamate, propyl-p-methoxycinnamate, isopropyl-p-methoxycinnamate, isoamyl-p-
Methoxycinnamate, 2-ethylhexyl-p-methoxycinnamate, 2-ethoxyethyl-p-methoxycinnamate, cyclohexyl-p-methoxycinnamate, ethyl-α-cyano-β-phenylcinnamate, 2-ethylhexyl-α -Cyano-β-phenylcinnamate, glycerylmono-2-ethylhexanoyldiparamethoxycinnamate and the like; 2,4-dihydroxybenzophenone as a benzophenone type;
2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4'-methylbenzophenone, 2-hydroxy-4-methoxybenzophenone, 4-phenylbenzophenone, 2-ethylhexyl-4'-phenylbenzophenone-2-carboxylate, 2-hydroxy-4-n-octoxybenzophenone, 4-hydroxy-3-carboxybenzophenone and the like But also: 3- (4'-methylbenzylidene) -dl-camphor, 3-benzylidene-dl-camphor, urocanic acid ethyl ester,
-Phenyl-5-methylbenzoxazole, 2,2'-
Hydroxy-5-methylphenylbenzotriazole,
2- (2'-hydroxy-5-t-octylphenyl)
Benzotriazole, dibenzalazine, dianisoylmethane, 4-methoxy-4'-t-butyldibenzoylmethane, 5- (3,3-dimethyl-2-norbonylidene)
-3-pentan-2-one, a benzene bis-1,3-diketone derivative described in JP-A-2-212579,
And benzoylpinacone derivatives described in JP-A-3-220153.

Examples of the water-soluble ultraviolet absorber include diethanolamine p-methoxycinnamate, sodium 2-hydroxy-4-methoxybenzophenone-5-sulfonate, tetrahydroxybenzophenone, methylherperidine, and 3-hydroxy-4-methoxycinnamate Sodium acid, sodium ferulate, urocanic acid and the like, and extracts of animals and plants such as yarrow, aloe, below mallow, burdock, salvia and the like, which have an ultraviolet absorbing effect, are exemplified.

Among these UV absorbers, a cinnamic acid-based oil-soluble ultraviolet absorber is particularly preferred.

When blending these UV absorbers,
It is preferable to mix 0.1 to 50% by weight in the whole composition,
Particularly, it is preferable to add 0.5 to 20% by weight, more preferably 0.5 to 10% by weight, since a higher UV protection effect can be obtained.

The cosmetic of the present invention includes various optional components used in ordinary cosmetics, quasi-drugs, pharmaceuticals, etc., in addition to the above components, as long as the effects of the present invention are not impaired.
For example, surfactants, oils, sterols, silicones, polysaccharides, amino acids, plant extracts, humectants, powders,
An oil gelling agent, a film forming agent, an anti-inflammatory agent, an antioxidant, a pH adjuster, and other components can be appropriately compounded.

The cosmetic of the present invention is a W / O emulsion type, O / W
It can be made into any dosage form such as emulsified, gel, solid, liquid, etc. For example, besides lotion, emulsion, cream, beauty serum, etc., makeup cosmetics such as foundation, face powder, lipstick etc. It can be.

[0030]

The monodispersed powder of the present invention has high transparency,
Moreover, it has an excellent UV protection effect, and is particularly suitable as a compounding component of cosmetics.

[0031]

EXAMPLES Next, the present invention will be further described with reference to examples, but the present invention is not limited to these examples.

The abbreviations used in the examples are as follows. St; styrene monomer NaSS; sodium styrenesulfonate APS; ammonium peroxodisulfate H ₂ O; distilled water

Example 1 (Production of Monodispersed Powder) Monodispersed polystyrene particles of the present invention were produced by soap-free emulsion polymerization. The composition of the monomer, initiator, and dispersion medium is: 40 parts St / 0.24 parts APS / 80 parts H ₂ O, and further adding 0.08 parts, 0.12 parts, or 0.16 parts of NaSS. Was used to control the particle size. The particle size and particle size distribution of the obtained polystyrene particles (weight average particle size /
Number average particle size) by a dynamic light scattering photometer (DLS-700;
(Manufactured by Otsuka Electronics Co., Ltd.) using a dynamic light scattering method. Table 1 shows the results.

[0034]

[Table 1]

Example 2 (Measurement of reflected light spectrum) The dispersion liquid of monodispersed polystyrene particles obtained in Example 1 was
It was applied on a glass plate, and the reflected light spectrum was measured using the apparatus shown in FIG. FIG. 2 shows the measurement results of the reflected light spectrum. In FIG. 2, the horizontal axis represents the wavelength of light, and the vertical axis represents the intensity ratio of the reflected light from the sample when the intensity of the reflected light from the glass plate is 0 and the intensity of the reflected light from the barium sulfate plate is 100. Particle sizes of 206 nm, 165 nm and 14
The monodisperse polystyrene particles of 7 nm show different reflected light spectrum charts, and the intensity peak of the reflected light shifted to the shorter wavelength side as the particle diameter was smaller. On the other hand, when monodispersed polystyrene particles were dissolved in chloroform and a polystyrene film having no ordered structure layer was similarly applied on a glass plate, no specific reflected light peak was observed.

Example 3 (Measurement of transmitted light spectrum) The dispersion liquid of monodispersed polystyrene particles obtained in Example 1 was
A film having a thickness of 0.1 mm was formed on a quartz plate, and the transmitted light spectrum was measured. FIG. 3 shows the measurement results of the transmitted light spectrum. In FIG. 3, the horizontal axis is the light wavelength, and the vertical axis is the transmittance. The transmitted light spectrum of monodisperse polystyrene particles having a particle size of 165 nm has a low transmittance of about 40% at a wavelength of 400 nm and a high transmittance of about 80% at a wavelength of 500 nm.
It indicates that it has UV reflectivity and high transparency. On the other hand, when monodispersed polystyrene particles were dissolved in chloroform and a polystyrene film having no ordered structure layer was similarly coated on a quartz plate, absorption of light having a wavelength of 300 nm or more was not confirmed.

Example 4 (Measurement of UV protection ability) Cosmetics having the composition shown in Table 2 were produced by a conventional method, and the UV shielding effect of each cosmetic was measured with an SPF analyzer (SPF-290).
ANALYZER; The Optometrics
Corporation). The results are shown in Table 2.

[0038]

[Table 2]

As is clear from the results shown in Table 2, the cosmetic of the present invention had a high SPF value and an excellent UV protection effect. Also, the transparency was high.

[Brief description of the drawings]

FIG. 1 is a diagram showing an apparatus used for measuring a reflected light spectrum in the present invention.

FIG. 2 is a view showing a reflected light spectrum of the monodispersed powder of the present invention measured in Example 2.

FIG. 3 is a graph showing a transmitted light spectrum of the monodispersed powder of the present invention measured in Example 3.

Claims (6)

[Claims] 1. A monodisperse powder which, when applied, forms a regular structure and has UV-selective reflectivity. 2. The monodispersed powder according to claim 1, wherein the regular structure is a regular structure layer emitting reflected diffraction light. 3. The monodispersed powder according to claim 1, which has UV-selective reflectivity at a wavelength of 250 to 400 nm. 4. When the average particle diameter measured by a dynamic light scattering method is 0.1 to 0.3 μm and the particle diameter distribution (weight average particle diameter / number average particle diameter) is 1.50 or less. Certain claims 1-3
The monodispersed powder according to any one of the above. 5. The method according to claim 1, which forms a regular structure on the skin.
5. The monodispersed powder according to any one of items 4 to 4. 6. A cosmetic comprising the monodispersed powder according to claim 1.